The present invention relates to a dental x-ray film holder and a method of aligning an x-ray tube with an x-ray film holder in a patient's mouth.
Intra-oral radiographs or x-rays are taken in general dental practices in an enormous and increasing number every year. Since the late 1920's, patients have been required to bite on tabs during bitewing x-ray examination. Over a period of years, dentists will accumulate a series of radiographs of his patients. which offers the dentist aid in diagnosing oral diseases as well as monitoring the patient's therapy. If the radiographs are of good quality and have been taken from similar angles, then the progression of approximal caries and the condition of the alveolar support may be realistically assessed. Unfortunately in many cases, little attention is given to the standarization of technique such as to allow variable comparisons, especially in the variables concerning the film position relative to the object and position of the x-ray tube in the x-ray focus.
Normal practice has been to hold film packets in place by a variety of film holding devices have been produced over the years for use in intra-oral radiography. A great variety of simple bitewing film holders have become available and these include self-adhesive tabs, slide-on cardboard loops, polystyrene, styrofoam, wood and plastic blocks, with or without localizing pointers. These simple holders have the advantage that they usually are better tolerated by the patients who may find the more elaborate film holdering aiming devices uncomfortable to bite on and therefore causing difficulty in maintaining film placement.
In recent years, there have been attempts made to aid in the free hand positioning of the x-ray tube head in order to achieve optimum beam angulation. This is particularly important for the bitewing projection in order to diagnose small carious lesions and avoid artifactual overlapping of contact areas. There have been extra oral aiming rods attached to film holders as well as the use of a target distance localizer fixed to the x-ray tube head consisting of a wire ring at the end of a long rod.
The prior patents for intra-oral dental x-ray film holders include the Ketcham patent for a mouth film holder for x-rays, U.S. Pat. No. 1,012,561 and the Raper U.S. Pat. No. 1,467,876 for a film packet for x-ray work. In the Vloch U.S. Pat. No. 1,974,936, a holder for x-ray film packets include wrapping the bite tab completely around a film packet. In the Kreider U.S. Pat. No. 2,240,336, a dental x-ray film holder has a bite tab extending from the film holder which has flange grooves for holding the film packet. In the Rinn U.S. Pat. No. 2,274,808, a bitewing for dental film packs has the tab completely surrounding the film packet. These typical prior intra-oral film holders of the bitewing type have various means for holding the bitewing or bite tab to the film packet but do not have means to align the film packet and teeth with the x-ray tube.
There have been bitewing instruments manufactured and commercially available for use in aligning film packets during a bitewing x-ray examination. These include the Rinn instrument which contains a ring on a connecting rod to be positioned which in turn has a film holder for holding the film packet thereon in the Rinn bitewing holder The Precision Instrument alignment apparatus operates in a similar manner. These beaming devices are claimed to be of great practical use in routine intra-oral radiography in helping operators achieve standardized technique with a reduction in the x-ray dosage and improvement in the image quality of the x-ray. The disadvantages with the aiming devices is that the discomfort in biting interferes with correct film placement.
Three major problems in producing a quality radiograph are horizontal overlap, concculling and poor film positioning thereby not maximizing number of teeth exposed on the film. The cause of horizontal overlap is that the primary beam is not directed at a right angle between the contacts of adjacent teeth. The cause of conecutting is that the x-ray tube does not completely cover the film therefore the x-rays do not irradiate the film in certain areas.
The present invention relates to a simplified bitewing x-ray film holder for intra-oral x-ray having alignment techniques added to the bitewing film holding tab and to a method of aligning the x-ray tube head with the bitewing film holding tab in a more accurate and standardized manner.